Most of the literature on scheduling of multi-product batch process does not consider the uncertainties in demand and variability in processing times. We develop a simulation based variable production schedule model for a multi-product batch facility assuming zero wait transfer policy and single product campaign. The model incorporates the demand uncertainties and processing time variability. The impact of demand uncertainties is evaluated in terms of total annual cost, which comprises of the backorder and inventory costs per year. The effect of variability in processing time is measured by the annual production time. We also develop a constant production schedule model that has uncertain demand arrival, but the schedule is independent of demand variations. We compare the variable production schedule model with constant production schedule model in terms of the total annual cost incurred and subsequent results are presented. The conclusion drawn from this comparison is that the total annual cost can be significantly reduced when the demand uncertainties are accounted for in the production schedule.